Master Insulinoma with Picmonic for Medicine

An insulinoma is classified as a pancreatic neuroendocrine tumor (PanNET). On histology, it is an insulin-producing neuroendocrine neoplasia of the B cells of the islets of Langerhans in the pancreas.

Insulinomas are benign in 90% of cases. These are the most common endocrine-disrupting tumors of the pancreas. Adenocarcinoma is present in around 10% of cases.

In 90% of cases, insulinoma is a solitary tumor. In the remaining 10%, it is associated with multiple tumors, possibly in the context of multiple endocrine neoplasia type 1 (MEN-1).

Whipple's triad represents the three most definitive criteria for diagnosing insulinoma. It includes symptoms of hypoglycemia, documented low blood glucose, and rapid subsidence of symptoms after carbohydrate intake.

The high amount of insulin this tumor produces causes blood sugar to drop. Initially, sympathetic output may be increased resulting in diaphoresis, tremors, headache, etc after which neuroglycopenic symptoms such as altered mental status and vision changes may occur. This is the first criterion in Whipple's triad.

If the blood glucose is low (e.g. < 50 mg/dL) during an episode of hypoglycemic signs and symptoms, this fulfills criterion #2 in Whipple's triad.

The final criterion is relief of symptoms with glucose administration.

In addition to lab values showing increased insulin levels from the tumor, an increased C-peptide level will also be seen. This is because insulin is being produced endogenously in this disease, which helps differentiate it from exogenous etiologies of hyperinsulinemia and/or hypoglycemia.

The therapy of choice for insulinoma is surgical resection. Normally these tumors are small, and thus can be operated on without complications.

In the case of a poor surgical candidate, therapy with diazoxide or octreotide - which inhibit insulin secretion - can be attempted.

In the case of a poor surgical candidate, therapy with diazoxide or octreotide - which inhibit insulin secretion - can be attempted.